台灣蝴蝶蘭之低溫逆境反應和PaCBF1和PaICE1表現的分析

Cold response in Phalaenopsis aphrodite and characterization of PaCBF1 and PaICE1

彭柏欣(Po-Hsin Peng)

指導教授 ： 林彩雲

國立清華大學/生命科學院/生物資訊與結構生物研究所/博士(2014年)

摘要

蝴蝶蘭為一種冬天開花的蘭科植物，廣泛栽培於亞洲許多熱帶國家。由於蝴蝶蘭是台灣主要經濟花卉之一，故在低溫等逆境下蝴蝶蘭生理及基因調控具有進一步研究之重要性。這篇論文主要探討臺灣白花蝴蝶蘭 (P. aphrodite) 對低溫及其他非生物逆境的反應，由我們的實驗結果得知臺灣白花蝴蝶蘭對低溫敏感，尤其在植株開花期，4°C處理的生長期植株比開花期植株葉片細胞膜穩定且光合作用效率較高。在分子層面，低溫誘導C-repeat binding factor1 (PaCBF1) 基因及可能受其調控的下游基因dehydrin1 (PaDHN1) mRNAs累積，但inducer of CBF expression1 (PaICE1) 的mRNA則持續表現。PaICE1可活化PaCBF1啟動子及存在該區域的MYC motifs，推測PaICE1可能藉由MYC motifs調控PaCBF1；PaCBF1在低溫下可活化PaDHN1啟動子，顯示PaCBF1可能參與低溫調控PaDHN1的表現。在未受低溫刺激的環境，大量表現PaCBF1基因的轉殖阿拉伯芥相較於野生型具有較高的逆境基因COR6.6及RD29a表現量，且在低溫處理後維持較好的細胞膜完整性。在此篇論文中我們提供證據說明在蘭科植物低溫逆境經由PaICE1蛋白調控PaCBF1基因表現，並誘導DHN等cold-regulated (COR) 基因表現達到降低低溫傷害，就我們所知這也是第一篇從蘭科植物選殖並分析CBF、DHN及ICE基因的論文。

關鍵字

低溫逆境 ； 臺灣白花蝴蝶蘭

並列摘要

Phalaenopsis is a winter-blooming orchid genus commonly cultivated in tropical Asian countries. Because orchid is one of the most economically important flower crops in Taiwan, it is crucial to understand its response to cold and other abiotic stresses. The present study focused on gene regulation of P. aphrodite in response to abiotic stress, mainly cold. Our results demonstrate that P. aphrodite is sensitive to low temperatures, especially in its reproductive stage. We found that after exposure to 4°C, plants in the vegetative stage maintained better membrane integrity and photosynthetic capacity than in the flowering stage. At the molecular level, C-repeat binding factor1 (PaCBF1) and its putative target gene dehydrin1 (PaDHN1) mRNAs were induced by cold, whereas inducer of CBF expression1 (PaICE1) mRNAs were constitutively expressed. PaICE1 transactivated MYC motifs in the PaCBF1 promoter, indicating that up-regulation of PaCBF1 may be mediated by the binding of PaICE1 to MYC motifs. PaCBF1 transactivated PaDHN1 at cold treatment, suggesting PaCBF1 was involved in the cold-regulation of PaDHN1. Overexpression of PaCBF1 in transgenic Arabidopsis induced AtCOR6.6 and RD29a without cold stimulus and maintain better membrane integrity after cold stress. Herein, we present evidence that cold induction of PaCBF1 transcripts in P. aphrodite may be transactivated by PaICE1 and consequently protect plants from cold damage through up-regulation of cold-regulated (COR) genes, such as DHN. To our knowledge, this study is the first report of isolation and characterization of CBF, DHN and ICE genes in the Orchidaceae family.

並列關鍵字

C-repeat binding factor ； cold stress ； dyhydrin ； inducer of CBF expression ； MYC motif ； Phalaenopsis aphrodite

參考文獻

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